I. Field of the Invention
This invention relates generally to a method and apparatus for insulating a kiln, and more particularly for insulating a kiln for drying lumber and for insulating a lumber predrying building, with walls that are virtually impervious to caustic moisture.
II. Prior Art and other Considerations
Kiln drying lumber is done in a high temperature atmosphere of nearly 100% relative humidity. The kiln drying building must be well insulated to hold the appropriate heat in the building. In the past, if moisture reached the insulation material, the insulation material lost most of its effectiveness rendering the building substantially unusable without repair.
It is expedient, therefore, that all moisture be kept from the insulation. In the kiln drying process the high temperatures and the acid released by the drying process are highly corrosive. The combination of high temperature, high humidity and high acidity, with pH frequently ranging to nearly as low as 3.0, defeat most attempts to keep moisture from the insulation in the building walls. The insulation technology used in lower temperature, lower humidity situations has not proven to be useful for kiln drying lumber.
Prior kiln drying buildings have been constructed using panels made of insulation encapsulated by aluminum cladding. The panels were prefabricated. The panels were joined to construct a building by aluminum extrusions and bolts or by lap joints with mechanical bolts. These kiln panels deteriorate very rapidly from a combination of thermal cycling, high relative humidity, and acid from the wood drying process. The insulation in the panels quickly become moist reducing its insulation value, and requiring replacement of the panel. The panels have also proven difficult and expensive to install as well as unattractive once installed.
Prior refrigeration insulation technology has not been concerned with the problems inherent in a high temperature, high relative humidity, high acidity environment. These conditions lead to corrosive conditions not faced in refrigeration type situations.